like an anti tax motive, they would probably be targeting the irs buildings. if it were some sort of anti federalism motivation, they would attack some other oh federal institution. but to bob's point, these are soft targets. it's exactly what zawahiri was calling for. we recovered from the materials of the site when bin laden was killed there was a debate going on between the leadership of al qaeda and its lieutenants where bin laden wanted them to continue to focus on these very dramatic events like 9/11, and the lieutenants, the so-called generation 2.0, wanted to say, look t at the end of the day that's great you did that, older generation, but we have to deal with the realities we're up against. and these low-level ied attacks at least allow us to get points on the board so anwar al al awlaki was supporting this effort. and the signature here does suggest there is a possibility of some type of violent islamic extremist connection. >> bob, the fbi running this investigation under huge pressure. the modern media age where even after two hours people are screaming for a result.